Production of solvents



July 28, 1942 J. E. HARVEY, JR 2,291,307

PRODUCTION OF SOLVENTS Filed March 14, 1941 wwwa;

Patented July 28, 1942 PRODUCTION OF SOLVENTS Jacquelin E. Harvey, Jr., Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia Application March 14, 19411, Serial No. 383,457

6 Claims.

The present invention relates to the production of valuable liquids from tars and fractions thereof, crude and/ or refined.

This application is a continuation in part of my application Sr. No. 352,669, filed August 14, 1940, for Production of solvents, copending herewith, as to all matter common to the two applications,

An object of the present invention is the subjection of tars and fractions thereof, crude and/ or refined, to the action of hydrogen in stepwise manner, whereby to provide refined solvents of increased solvency and boiling range.

A further object of the present invention is the production of refined solvents of lowered corrosivity, the characteristics of which are, among other things, dependent upon hydrogen supply, as hereafter explained.

Other objects of the present invention will be apparent from the following disclosures.

Suitable starting materials of the present invention include tars and fractions thereof derived from coal and petroleum and gas or gases of carbon content, as for instance coke oven tar, water gas tar, gas house tar, and tars of aromatic content in general, tars produced by cracking hydrocarbons; tars resulting from the action of hydrogen on hydrocarbons; tars resulting from polymerization; high boiling aromatic extracts of carbonaceous substances; high boiling hydrocarbons of aromatic content having olei'lnic and/or naphthenic content.

Especially attractive as starting material is high temperature coke oven tar which is available in large quantities at low prices.

The present invention may be viewed broadly as a process for the production of refined solvents of lowered corrosivity by subjecting the starting material, in step-wise manner, to the controlled action of hydrogen whereby to produce said solvents having increased boiling points and enhanced solvency.

The following examples will illustrate the general principle upon which the practice of the present invention is based, as well as the process of the present invention.

The invention will be understood from the following description of illustrative steps comprising various methods of securing the objects of the invention, when read in connection with the accompanying drawing wherein the gure is a diagrammatic sketch of an apparatus for carrying out a form of the process of the invention and wherein the nature of the step carried out in each chamber and the contents thereof are indicated by legend.

Erample 1.-A sulfur bearing coal tar creosote, characterized by in excess of 1% coke residue, a specific gravity of in the order of 1.06, and substantially 25% residue above 355 C. is subjected to the action of hydrogen at 375 C. and 200 atmospheres pressure whereby ,to lower sulfur content, thereby lowering corrosivity, at least providing for lowered corrosivity in the 1inished material as hereinafter described. The creosote of lowered corrosivity is passed in liquid phase through a high pressure reaction vessel while simultaneously owing hydrogen therewith in the presence of a molybdenum oxide catalyst at a temperature of 400 C. and 250 atmospheres pressure. The time of contact is one hour and the flow of gas 15,000 cubic feet per barrel sulfur refined creosote. The beneiiciated creosote upon inspection will be found to have a lowered boiling range, specific gravity and viscosity. Some of the lower fractions of the beneficiated creosote will have a lowered solvency as compared to solvents extant of a comparable boiling range.

The beneflciated material is stripped to an upper limit of 300 C. and the distillate is passed through a high pressure reactor at 155 C, and 200 atmospheres pressure while contacting a molybdenum oxide catalyst. The flow of hydrogen is so controlled as to induce a solvent having, as compared to the intermediate starting material, increased boiling points and increased solvency.

The solvent so produced may be fractionated to provide refined `solvents of lowered corrosivity of any boiling range within the limitations of the finally processed material, as for instance:

C. Benzol 'T8-120 Toluol -150 Hi-iiash naphtha -200 Heavy naphtha 150-290 Plasticizers -360 or others.

The refined solvents of lowered corrosivity serve as substitutes for the commercial solvents noted.

In the foregoing examples, it will be noted that the present process provides a method for contacting the starting material with hydrogen whereby to lower sulfur content, thereafter, contacting the material of lowered sulfur content with hydrogen whereby to produce an intermediate product of lowered solvency, speciiic gravity, boiling range and viscosity; stripping from the beneiiciated material a fraction thereof and subjecting at least a portion of the distillate to the controlled action of hydrogen whereby to enhance solvency and produce increased boiling points thus providing the refined solvent of lowered corrosivity of the present invention.

Looked at one manner, the present process provides a method for treating sulfur bearing tars of aromatic content, and fractions thereof, with hydrogen in step-wise manner whereby to produce rened solvents of lowered corrosivity said solvents being characterized by increased solvency and boiling points when compared to the intermediate parent material, as. above disclosed. The said step-wise action of hydrogen following the sulfur reduction step being eiected by pro viding hydrogen in flow that depolymerizes ring multiplicities thereby inducing lowered specific gravity, boiling range, and solvency, and later, by providing hydrogen in ow thatincreases boil, ing points and solvency.

The aforenamed step-wise action of'. hydrogen thus provides a methody for securing refined solvents of lowered corrosivity from heavy or. high boiling hydrocarbons of aromatic content, said. high boilers characterized by the presence'of ring multiplicities of great thermal susceptibility.

Example 2.-A sulfur containing coal tar,

. specific gravityLlGel, a coke residue in excess of and in excess of 35% boiling at` 355 C. is subjected to the action of hydrogen at390" C. and 200 atmospheres pressure for such arlength of time as to lower sulfur content. The coal tarof lowered sulfur content is passed in liduidrph-ase` through a high pressure reactionchamber whilesimultaneously flowing'hydrogen therewith at a pressure of 380 atmospheres anda temperature of 420 C. Time of Contact is one hour, catalystvanadium oxide, and flow of hydrogen 15,000` cubic feet per barrel feed stock. The thus treated coalv tar is found to have an overall lowered specific gravity, viscosity and coke residue,- and in some of its fractional partsa lowered solvency.

as compared to solvents extant. The beneciated tar is then stripped to an upper limit of 360o C. and the distillate subjected to the action cf. a flowL of hydrogen at 450 C'. and 225 atmospheres pressure, with the time of Contact and gas flow so controlled as to increase boiling points and solvency. Y

EampZe-A high boiling coa-l tar fraction of sul-fur content, initial boiling point of substantially- 250 C. is subjected to the action of hydrogen at 375 C. and 390 atmospheres pressure for such'a time as to reduce sulfurcontent. The coal tar of reduced sulfurl content is then passed in liquid phase through a high pressure reaction chamber while simultaneously flowing hydrogen therethrough at a temperature of 410 C. and 300' atmospheres pressure; catalyst, molybdenum ox'- ide. Upon inspection the beneciated coal tar fraction will beY found'to have a lowered specic gravity, viscosity, coke residue, boiling range, and, in the case of some fractional parts of the benifciated material a lowered solvency. as compared to'solvents extant.

The beneciated material is stripped to 290? C. and the distillate subjected to the action of hydrogen Yat 535 C. and 300Y atmospheres pressure;

flow of hydrogen 5,060 cubic` feetzper barrel feed..

and the time so controlledas to increase boiling points and solvency. The time in the last step may. be a fractional minute. or more, as for instance several minutes.

The residues incidental to the stripping actions aforenamed may be recycled or used as an article of commerce of enhanced value, as for instance binders or the like.

The starting material of high carbon content, as for instance, high temperature coke oven tar in its raw state, is characterized by such a percentage of high molecular complexes or polymerized products that the refined solvents'of lowered corrosivity of the present invention as representing total conversion of the material remaining liquid are not possible of manufacture therefrom directly, but must be produced in step-wise manner as explained, whereby among other thingsthe action of hydrogen depolymerizes said molecular complexes contained in the starting material.

The depolymerized or partially depolyrnerized tar or fractions thereof of lowered sulfur content is then stripped of a percentage of its low ends whereby toV provide the intermediate parent material. of the. refinedV solvents. of lowered corrosivity, said refined solvents characterized. by increase of boiling points and solvency; the residue incidental to said stripping` may, because. of its depolymerized or. partially depolyme-rized conditions serve as recycled. material tothe end that conversion of the starting material in the percentage remaining. finally. liquid approaches volume for. volume of the starting material into `the refined. solvents of the present invention.

In the conversion of starting materials, partially or. approaching unity, into` the refinedsolvents. of lowered corrosivityv of the present inven-n tion temperaturesas low as 3009 C. may be employed; pressuresas low as 50 atmospheres may be used.v However, temperatures'and pressuresof an increased range provideY better commercial practice. The time element is desirabl-y that period which affords commercial recoveriesof-the productsof, and. incidental to, the present` invention. Temperatures are preferred that cause nosubstantial coking.

Gas ows. are usually hel-d in excessof 3.900v

cubicv feet. per barrel` material treated. In the stepwise application of hydrogena fewl trialsy when usingany of the starting materialswi-ll -determine thegas ow, when coordinated with the selectedtemperature and pressure condi-tions to eiect said depolymerizing. The gas-flow in this instance may be a variable quantity because of the varying ranges of coordinated temperature and pressure thatmayA be selected. Whenusing any chosen coordination of temperature and pressure, a few trials will readily 'determine the des1rable gas ow. For a given coordination of Vtemperature and pressure, the gas new in Vthe last instance is lower than the gasiiow in the preceding instance.

Using some` starting materials, a gas-:flewl of 15,000-18,000 cubic feet per barrel., or higher, hasproven Vsatisfactory for depolymerizing condi-V tions, and, gas flow in the. order of 6,000e8,0.00.or lowerY when increasing solvency, and boiling points has proven satisfactory.

Viewed broadly, the hydrogen flow in theY in stance of obtaining depolymerizing conditions hnay be lower than 10,000 cubic feet per barrel eed.

In the hydrogen action that reduces sulfur content, the actionrof hydrogen may be effected in an autoclave or in a continuous plant, and in the event continuous practice is used, the flow of gas is maintained so as to assist in reduction and removal from the reaction zone of theV sulfur content, the while inducing no substantial percentage of carbon, nor percentages of liquid chain structures that would preclude the provision of the refined solvents of superior solvency as stated.

By the term beneciated as used herein and in the appended claims is meant the starting material at least once subjected to the action of hydrogen in accordance with the present process.

After the starting tar has been subjected to depolymerizing action, the stripping step may be effected at any point selected within a Wide range to provide a cut capable of providing, after further processing, substitutes for the boiling range or ranges of benzol, toluol, xylol, naphthas, and/or plasticizers.

Thus, the depolymerized starting material may be cut according to the need at hand, said cut being then subjected to the action of hydrogen that increases solvency and boiling points.

The catalysts of the present invention are oxides; as for instance oxides of metals of the 6th and 8th periodic groups; the om'des of other groups may be used, however, diicultly reducible oxides are preferred. The catalyst in any form may be employed, as for instance, pellets, comminuted, supported on carriers or the like.

If desired, comminuted catalysts may be used in the hydrogen step characterized by depolymerization; and in the step characterized by solvency increase, a rigid catalyst may be used.

By the term multiplicity of rings, high molecular complexes and polymerized products are meant high boiling fractions of aromatic content, a portion of which at least may be viewed as ring multiples; or said terms, any or all, may be used to describe high boiling fractions of the starting material which because of high carbon content are especially susceptible to thermal degradation.

When subjecting high boiling fractions of the starting material to the process of the present invention, it may be desirable prior to the depolymerizing step, or the sulfur reduction step, to at least partially depolymerize the molecular complexes by use of a solvent. Said solvent may be added in a small amount, or up to volume for volume or more may be used. Refractory solvents may be desirable, but others more susceptible to the reactions inherent in and to the present process are usable.

Concerning solvents, it may be said that tar itself, as for instance high temperature coke oven tar, is constituted of high molecular complexes dissolved, cut back or depolymerized with a solvent, said solvent being the lower boiling fractions of said tar.

The action of hydrogen as aforestated may be effected in one or more cycles or chambers, with or without releasing the pressure and with or without variation of process controls, including changes in either temperature, pressure and/or gas flow.

Various modes of practicing the present invention are possible; for instance the depolymerized starting material may be stripped as for instance by gas movement; the low ends thus stripped may then, with or without releasing pressure, be subjected to the further action of hydrogen that increases solvency and boiling points. Or the desired stripped material may be obtained by partial release of pressure which would correspond to the fractional recovery desired or predetermined.

The process may be practiced in an autoclave and/or a single high pressure reaction chamber, a series thereof, a parallelism thereof, including a multiplicity thereof.

The refined solvent of the present invention characterized by lowered corrosivity and superior solvency may, as aforestated, be fractionated to provide solvents and/or plasticizersv 0f Various boiling ranges, and in the instance where solvents are processed from a deep cut on the depolymerized material, the highest boiling fraction thereof may serve as a substitute for certain plasticizers.

In the first cycle of hydrogen action that reduces sulfur content, said reduction of sulfur may be accomplished in the presence of a catalyst. Catalysts effective in the presence of hydrogen are usable, as for instance the oxides and/or suldes of molybdenum, vanadium, uranium, cobalt, tin, manganese, tungsten, or the like. Example 4.-It has been discovered that when subjecting certain mixtures of refined coal tar fractions to the action of hydrogen in accordance with the present process for the production of solvents and/or plasticizers the formerly accepted teaching that product increment, depolymerization and/or hydrogen absorption are 1inear functions of the time, is not followed.

When subjecting a mixture of crude coal tar fractions boiling predominantly above 250 C. or 275 C. to the action of hydrogen, research has disclosed that the newly induced products, depolymerization and/or hydrogen absorption are linear functions of the time. As an example, when the above mixture of crude coal tar fractions is subjected to the action of hydrogen for 2, 5, and S-hour periods, the newly induced products, depolymerization and/or hydrogen absorption were linear functions of the time element.

One of the preferred starting materials of the present process is a mixture of rened coal tar fractions boiling predominantly above 355 or 380 C. Such a starting material is conveniently the .final residue resulting from evaporating coal tar to dryness or substantial dryness and then stripping Wood preservative from the distillate. This final residue mass of refined coal tar fractions is an especially suitable refined pitch to be used as starting material of the present process. However, in contradistinction to the mixture of crude coal tar fractions boiling predominantly above 250 or 300 C., when the aforenamed preferred starting material is subjected to the action of hydrogen for production of solvents and/or plasticizers, the newly induced fractions, depolymerization and/or hydrogen absorption are not, as described for the other mixture of coal tar fractions, linear functions of the time. A critical period of treatment by or with hydrogen exists, and which if exceeded causes loss of newly induced fractions, polymerization and/or lessened hydrogen absorption on certain fractions of the preferred starting material under I treatment.

element, loss of induced products, polymerization and/or lessening of hydrogen absorption would occur. When treating the refined coal tar pitch by or with hydrogen, the. critical'time element is in the order of about three hours.

In the disclosures made herein and in the appended claims distillate removal of low boiling portions from the beneflciated material is considered the equivalent of fractional removalby gas movement, solvent action or the like. rIhe converse also obtains.

A refined coal tar pitch selected fromV the Y group boiling predominantly above, and above,

355 C. and characterizedby a coke residue in excess of 2% is subjected to the. actionY of hydrogen at 390 C. and 200 atmospheres pressure whereby to lower sulfur content, thereby lowering corrosivity, at least providing for lowered corrosivity in the nished material as here.- inafter described. the purpose of lowering sulfur content is so controlled as to induce no substantialV percentage of solvent increment. sulfur content is then passed in liquid phase through a high pressure reaction vessel while simultaneously flowing hydrogen therewith. in the presence of an oxide catalyst selected from the group comprising the sixth and eighth periodic groups, at a temperature of 430 C. and a pressure of 300 atmospheres. The time of contact is two hours and the flow of hydrogen 15,000 cubic feet per barrel feed stock. The beneiiciated refined pitch upon inspection willl be found to have a lowered coke residue, specific gravity, viscosity and boiling range. Solvency in some of the lower fractions of the beneciated refined pitch will have a lowered solvency as compared to solvents extant of a comparable boiling range.

The beneciated refined pitch is stripped to an upper limit of 290 C. and the distillate is passed through a high pressure reactor at 495 C. and 200 atmospheres pressure. lThe flow of hydrogen is chosen from the range below 6,000 cubic feet per barrel material treated and is so selected that, when coordinated with the time element, solvent properties will be induced andthe overall treated material will have increased boiling points.

The solvent so produced may be fractionated to provide fractional cuts as noted elsewhere herein.

The residue resulting from the provision of the intermediate starting material may be recycled if desired for further solvent production. The residue is of a more liquid nature than. a comparable cut on the startingmaterial indicating that the high boiling ends which may be described as including` multiplicity of ring struc'- tures had been, at least, either saturated or partially saturated, thus providing the initial step in the stepwise conversion of substantially the entirety of the refined pitch remaining liquid under process conditions into the rened solvents of lowered corrosivity of the present process.

In the instance of the solvent recovered to an upper limit of' 290 C., as above described, the

Vsolvent cut maybe divided to provide solvents of various boiling ranges as may be dictated by necessity. When providing the intermediate starting. material of the present process, and in the event such provision is made by taking a deep cut on the beneciated refined pitch, the

The action of hydrogenfor The refined pitch of lowered tofore described, may provide high boiling fractions having plasticized properties.

WhenY subjecting the refined coal tar pitch to the action. of hydrogen for the production of solvents in accordance with the present process, the hydrogen action characterized by lowered coke` residue, specific gravity and viscosity is controllably held at or below the critical timeperiod, for if suchY is exceeded adverse reaction will occur. As an example, if the critical timeperiod is exceeded, instead of fractional increment, depolymerization and/or hydrogen absorption being linear functions of the. time element, the reverse will obtain. In other words, if the critical time period is exceeded, fractional in'- crement, depolymerization and/orhydrogen absorption will not be linear functions ofthe time element, it having been found, among other things, that a period in excess of that which is critical will provide for loss. of fractional increment and/or polymerization.

The critical time element in the instance of treating the reiined pitch with hydrogen is in the order of about three hours, and the present process is predicated on the employment. of the critical, or less than the critical, time element.

The rened solventsof lowered corrosivity as being the conversion product of the reiined pitch are of superior quality and areA characterized by a preponderance of ring structures.

When reference is made to high molecular complexes contained in the starting material, and when the starting material contains low boiling fractions thatare not considered high molecular complexes', it is of course obvious that theV boiling fractions have been removed, as for in-` stance tars from which solvent oils have been removed. Viewed broadly, the starting Inaterials of the present process are tars of aromatic content, fractions of said tar more viscous than the starting material due to'removal of low boiling fractionsfrom the starting material, highV boiling fractions and pitches;

It will be seen that by reductionof sulfur content of the material under treatment during any stage of hydrogen action, the oxide catalyst used during subsequent stages is at least partially protected from the effect of the sulfur.

The evaluation of solvent poweris conveniently accomplished by finding the well-known aniline point or kauributanol number. The evaluation of plasticizing properties is conveniently accom plished by recourse to methods. suggested in Chapter VI, The Technology of Solvents by Dr. Otto Jordon, Mannheim, Germany, translated by Alen D. Whitehead; Chemical Publishing Company of New York, Inc., New York, New York.

Minor changes may be made without departing from thelspirit of the invention.

I claim:

1. In the production of a solvent from the -sulfur containing refined pitch produced by overhead materialto recover a liquid useful asa deep'cut after further hydrogen action, as here- 75 wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: Vsubjecting said' higher boiling fraction to the action Vof hydrogen at a temperature and pressure of at least 300 C. and 50 atmospheres, respectively, and for such a period of time as to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high flow of hydrogen in the presence of an oxide catalyst for a period not in excess of about three hours at a pressure and temperature in excess of 50 atmospheres and 300 C., respectively, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneciated material; and increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 300D-8000 cubic feet per barrel material treated at a pressure above about 50 atmospheres and a temperature of l50-535" C., to produce a solvent.

2. In the production of a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen whereby to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high flow of hydrogen in the presence of an oxide catalyst for a period not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneciated material; increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 300D-8000 cubic feet per barrel material treated; and fractionating the last named beneficiated material to segregate a solvent.

3. In the production of a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen whereby to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relative high ow of hydrogen in the presence of an oxide catalyst for a period not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneciated material; increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low ow of hydrogen within the limits of about 300D-8000 cubic feet per barrel material treated; and fractionating the last named beneciated material to provide a solvent boiling preponderantly between 100 and 150 C.

4. In the production of a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen whereby to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high flow of hydrogen for a period not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneciated material; and increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low ow of hydrogen not in excess of about 8000 cubic feet per barrel feed stock, to produce a solvent.

5. In the production of a solvent from the sulfur containing rened pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen at a pressure and temperature of at least 50 atmospheres and 300 C., respectively, and for such a time as to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high flow of hydrogen in the presence of an oxide catalyst for a period not in excess of about three hours and at a pressure in excess of about 50 atmospheres and a temperature selected from the range above 300 C., whereby to avoid polymerization; stripping newly induced fractions from the beneciated material; and increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 300C-8000 cubic feet per barrel material treated at a pressure above 50 atmospheres and a temperature of 450-535 C., to produce a solvent.

6. In the production of a solvent from the sulfur containing rened pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen whereby to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high flow of hydrogen in the presence of an oxide catalyst at a temperature and pressure in excess of about 300 C. and about 50 atmospheres, respectively, for a period not in excess of about three hours, whereby to avoid lowered hydrogen absorption; stripping newly induced fractions from the beneciated material; and increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 3000-8000 cubic feet per barrel material treated, to produce a solvent.

J ACQUELIN E. HARVEY, JR. 

